Prepare all ingredients by dicing the onion and mincing the garlic.
In a large skillet, heat olive oil over medium heat. Sauté the onion for 3-4 minutes until soft, then add garlic and cook for 1 minute.
Add ground beef to the skillet, breaking it apart as it cooks until browned, about 5-7 minutes. Drain excess fat.
Stir in diced tomatoes, heavy cream, Italian seasoning, salt, and pepper. Bring to a gentle simmer.
Cook orzo pasta in a separate pot according to package instructions, about 8-10 minutes. Drain and set aside.
Combine cooked orzo with the sauce in the skillet, stirring gently for 2-3 minutes. Sprinkle mozzarella cheese on top and cover to melt.